1. Field of the Invention
This invention relates to the development of photographic materials, and in particular to methods for the selective silvering of photographic materials.
2. Background of the Invention
The art of producing black and white, monochrome, and color photographs and other photographic materials is well-developed and understood. The steps to produce black and white or monochrome materials generally include application of a developer, a fixing bath, washing, and finally drying the developed film or paper. The production of color photographs usually includes all previously listed steps and, additionally, the application of a bleach bath, prior to the fixing bath. These basic steps have remained unchanged for decades.
A more recent development in the art is the creation of photographs which incorporate "special effects" which enhance the visual appeal of the end product. One such special effect is the "silvering" of black and white photographs.
It is known within the art that black and white, or monochrome, photographs may be treated with chemical toners or developers to produce mirror-like reflective images of metallic silver (in appearance and composition). The resulting visual effect is sometimes referred to as "silvering", "silver toning" or "mirroring".
Conventional "black and white" photographic imaging performed on films, papers or other materials coated with silver halide emulsions lacking color couplers, renders dark (usually black) metallic silver images on backgrounds having the color of the base onto which the emulsion was coated (usually white, transparent, or of a light color value). Image shadows and midtones result from exposure of the silver halides to radiant energy and their subsequent reduction to metallic silver through the use of conventional developers. Highlight qualities (such as color, texture, and composition) are given by the base material.
However, it is possible to process finished black and white photographic images, as well as films, papers, and other materials sensitized with conventional black and white photographic emulsions, with chemical toners or developers (such as Halo-Chrome toner, marketed by Rockland Colloid Corp., and Silver Bronze Mirror Developer, marketed by Tetenal) that act upon silver salts (usually silver halides) to produce mirror-like reflective images of metallic silver (in appearance and composition). The resulting visual effect is sometimes referred to as "silvering", "silver toning" or "mirroring". Herein it shall be mostly referred to as "reflective silvering" or simply "silvering" in order to describe both the visual and the chemical nature of the light-reflecting metallic silver that is produced.
It is known within the art that reflective silvering of black and white, or monochrome, photographs can be obtained through either indirect or direct processing with chemical toners or developers such as Halo-Chrome toner or Silver Bronze Mirror Developer. The end result is either silver and white or black and silver images. In the latter, black light-absorbing metallic silver is also present in the final image.
In the direct process, reflective-silvering is carried out after the black and white photographic image has been developed with a conventional black and white developer, but before it has been fixed, because fixing removes silver halides by making them soluble. Instead of a black and white photograph, the result is a black and reflective silver photograph. The black areas and the silver areas of the image differ in appearance, but both are composed of metallic silver (Ag). The background color, which is normally given by the color of the material onto which the photographic emulsion is coated, is silver "toned" because the unexposed silver halides (which are normally removed by fixing) were converted to reflective silver, rather than to the black-looking silver that results from exposure and treatment in a conventional black and white developer.
The indirect process for reflective silvering is carried out on finished (normally developed, fixed, and washed) black and white photographic images. Because they contain no silver halides, their black areas (composed of black metallic silver) must be chemically converted to silver halides or other silver salts, through the use of a "bleach" bath. After bleaching and washing, a reflective silvering toner or developer bath is applied to the photograph. The result is a silver and white photograph. Areas which were previously composed of black-looking silver become silver "toned", because the black silver is converted to a silver halide or silver salt, which is subsequently converted to reflective silver. The background remains white (or the color of the material onto which the emulsion was coated) because it contained neither silver nor silver halides or salts.
It is not known within the art that reflective-silvering may be performed on color photographs. For example, the instructions for Silver Bronze Mirror Developer make no mention of the introduction of color into silvered prints. The instructions for Halo-Chrome toner merely mention the possibility of obtaining "a colored background, if desired, by using Rockland Printint" on prints silvered through the indirect process. Although not mentioned, the photographic base (usually white) can also be colored through the use of almost any color pigment or dye (water-colors, oil paints, food dyes, etc.) to obtain a silver and color image, when combined with indirect reflective-silvering carried out with Halo-Chrome, Silver Bronze Mirror Developer, or similar toners or developers. And, of course, a silver and color image can also be obtained through indirect reflective silvering carried out on a color paper or base coated with a black and white photographic emulsion.
However, prior to the invention described herein, it was not known within the art to produce photographic images that combine areas possessing the qualities of full-color photographs with either reflective silver or black on reflective silver areas, or black. In addition, it was not known how to produce black, reflective-silver, and white (or the color of the base onto which the emulsion was coated) photographic images that may be colored, if desired, through the use of pigments, dyes, toners or other means. In addition, it was not known how to produce black, reflective silver, monochromatic color and white (or base color) photographs, that comprise areas possessing the qualities of a toned or color-coupler developed photograph (monochromatic color or monochromatic color and white) with either reflective silver, or black and reflective silver areas, to which coloring may be incorporated through the use dyes, pigments, additional toners, or other means. Finally, it was not know how to produce monochromatic color, silver, and white (or base color) photographic images, that comprise areas possessing the qualities of a toned or color coupler developed photograph with the qualities of an indirectly silvered black and white material, to which coloring may be incorporated through the use of dyes, pigments, additional toners, or other means.